Wl 

 (leaf 2) 



On account of its extensive underground system of rootstocks, 

 Forsling 2 reports the use of western yarrow, as well as of sweet sage, 

 as a soil binder in certain types of erosion control on the Wasatch 

 Plateau in central Utah. When such plants are started near the 

 edges of small gullies, their rootstocks soon spread down in all direc- 

 tions across the depressions and serve to catch particles of sediment 

 from water flowing past them, thus forming small alluvial fans and 

 checking surface run-off. 



In addition to this vegetative propagation by rootstocks or rhi- 

 zomes, western yarrow also has fairly strong seed habits. It pro- 

 duces flowers practically throughout the summer, beginning as early 

 as May or as late as September in the higher mountains ; subsequently 

 there is, in the case of the early-flowering plants, a long period of 

 seed production. The late-flowering plants, however, often are un- 

 able to set seed. 



The leaves of western yarrow are mostly basal, often forming 

 rosettes. These lower leaves are stalked and are from 2 to 8 inches 

 long, but the unpaired (alternate) stem leaves become increasingly 

 shorter up the stem and are either stalkless (sessile) or nearly so. 

 The dense flower clusters at the ends of the stems are somewhat 

 flattened or convex like the top of a derby hat. What appear to be 

 individual flowers are really flower heads, consisting of a group of 

 flowers (both ray and disk flowers) attached to a common base 

 (receptacle), and closely surrounded by a series (involucre) of 

 small bracts (phyllaries) that overlap like shingles. 



Common yarrow (Achille'a millefo'lmm), a native of the Old 

 World, is a widely distributed weed in the eastern part of the United 

 States and in portions of the West. It is a taller, smoother, and 

 greener plant than western yarrow, and has long been used for me- 

 dicinal purposes. Its flowers are markedly aromatic and its leaves 

 possess astringent properties. It is very probable that western 

 yarrow (which is so closely related to common yarrow that some 

 botanists consider it merely a variety of the former, and not a 

 separate species) could be put to similar medicinal uses. Indians 

 are said to have employed western yarrow as a mild laxative. 



2 Forsling, C. L. A STUDY OF THE INFLUENCK OF HERBACEOUS PLANT COVER ON SURFACE 



RUN-OFF AND SOIL EROSION IN RELATION TO GRAZING- ON THE WASATCH PLATEAU IN UTAH. 



U. S. Dept. Agr. Tech. Bull. 220, 72 pp., illus. 1931. 



